Doc. No.:   WG21/N0843=X3J16/96-0025
                                     Date:       30 Jan 1996
                                     Project:    C++ Standard Library
                                     Reply to:   Nathan Myers
                                                 <ncm@cantrip.org>
 
        Clause 20 (Utilities Library) Issues (Revision 3)
 
** Revision History:
 
   Revision 0 - 22 May 1995 [was Version 1]
   Revision 1 - 09 Jul 1995 [was Version 2] (edits before Monterey)
   Revision 2 - 26 Sep 1995 (pre-Tokyo)
   Revision 3 - 30 Jan 1996 (pre-Santa Cruz)
 
** Introduction
 
This document is a summary of issues identified for the Clause 20,
identifying resolutions as they are voted on, and offering recommendations
for unsolved problems in the Draft where possible.
 
---------------
 
** Work Group:     Library: Utilities Clause 20
** Issue Number:   20-014
** Title:          allocator could be a template again
** Sections:       [lib.allocator.requirements], [lib.default.allocator]
** Status:         active
 
** Description:
 
In many containers, what one allocates is not objects of type T, but
objects of type (e.g.) Node<T>.  Therefore, in most cases the
container would be passed an allocator<T> when what it needs is
an allocator< Node<T> >, and possibly other instantiations as well.
 
** Discussion:
 
A separate proposal spells out the details.
 
1. A template constructor:
 
  template <class U>
    allocator(const allocator<U>&) throw();
 
2. and a member template containing a typedef:
 
  template <class U> struct rehost { typedef allocator<U> other; };
 
These two changes permit a container to construct an allocator
of the required type, given one for any other type.
 
** Proposed Resolution:
As in N0790 = 95-0190, Allocator Cleanup.
 
** Requester:      Myers
 
---------------
 
** Work Group:     Library: Utilities Clause 20
** Issue Number:   20-010
** Title:          auto_ptr specification wrong.
** Sections:       20 [lib.auto.ptr]
** Status:         active
 
** Description:
The specification for auto_ptr in the July Draft did not match
the defining proposal, in many details.  I don't know if Greg
is satisfied yet.
 
** Proposed Resolution
Change the specification to match the resolution accepted by
the committee.
 
** Requestor:      Greg Colvin
** Owner:
 
---------------
 
** Work Group:     Library: Utilities Clause 20
** Issue Number:   20-020
** Title:          Template constructor for pair<>
** Sections:       [lib.pairs]
** Status:         active
 
** Description:
 
make_pair() doesn't do what is needed for its most common use:
constructing pairs for maps.  A small change in pair<> would
solve the problem.
 
** Discussion:
 
** Proposed Resolution:
 
Add to pair a template constructor:
 
  template <class U, class V> pair(const pair<U,V>& p);
 
  Effects: initializes members from the corresponding members
    of the argument, performing implicit conversions as needed.
 
** Requestor:      Nathan Myers <ncm@cantrip.org>
** Owner:
 
---------------
 
** Work Group:     Library: Utilities Clause 20
** Issue Number:   20-023
** Title:          pair<> should have typedefs
** Sections:       [lib.utilities]
** Status:         active
 
** Description:
 
Given a pair, one cannot get the types of the elements T1 and T2.
 
** Proposed Resolution:
 
In [lib.pairs]:
 
  Add to struct pair:
 
    typedef T1 first_type;
    typedef T2 second_type;
 
[note: this is now part of omnibus proposal N0845 = 96-0027.]
 
** Requestor:      Myers
** Owner:
 
---------------
 
Closed issues:
 
** Issue Number:   20-001
** Title:          Allocator needs operator ==
** Resolution:     passed
 
** Issue Number:   20-002
** Title:          allocator::types<> has no public members
** Resolution:     passed
 
** Issue Number:   20-003
** Title:          Allocator requirements incomplete
** Resolution:     passed
 
** Issue Number:   20-004
** Title:          allocator parameter "hint" needs hints on usage
** Resolution:     passed
 
** Issue Number:   20-005
** Title:          Default allocator member allocate<T>() doesn't "new T".
** Resolution:     passed
 
** Issue Number:   20-006
** Title:          allocator::max_size() not documented
** Resolution:     passed
 
** Issue Number:   20-007
** Title:          C functions asctime() and strftime() use global locale
** Status:         closed by default (Tokyo)
 
** Issue Number:   20-008
** Title:          construct() and destroy() functions should be members
** Resolution:     passed
 
** Issue Number:   20-009
** Title:          Allocator member init_page_size() no longer appropriate.
** Resolution:     closed
 
** Issue Number:   20-011
** Title:          specialization of allocator::types<void> incomplete
** Resolution:     passed
 
** Issue Number:   20-012
** Title:          get_temporary_buffer has extra argument declared
** Resolution:     passed
 
** Issue Number:   20-013
** Title:          get_temporary_buffer semantics incomplete
** Resolution:     passed
 
** Issue Number:   20-015
** Title:          class unary_negate ill-specified.
** Resolution:     passed
 
** Issue Number:   20-016
** Title:          binder{1st|2nd}::value types wrong.
** Resolution:     passed
 
** Issue Number:   20-017
** Title:          implicit_cast template wanted
** Status:         closed, no action (Tokyo)
 
** Issue Number:   20-018
** Title:          auto_ptr::reset to self
** Status:         closed, implemented choice 2 (Tokyo)
 
** Issue Number:   20-019
** Title:          no default ctors on many lib classes
** Status:         closed, no action (Tokyo)
 
** Issue Number:   20-021
** Title:          should pair<> have a default constructor?
** Status:         closed, implemented (Tokyo)
 
** Issue Number:   20-022
** Title:          unary_compose and binary_compose missing.
** Status:         closed, no action (Tokyo)